Morphological Variation of Pisaster Orchraceus in Response to Wave Exposure
Datum
2016-06
Autor:innen
Bjorkquist, Alyssa
Zeitschriftentitel
ISSN der Zeitschrift
Bandtitel
Verlag
University of Oregon
Zusammenfassung
Pisaster ochraceus (the Ochre Sea Star) is a keystone predator in the NE Pacific
that regulates intertidal diversity through consumption of space-competing organisms.
Individuals inhabit a broad range of habitats ranging from sheltered coves to exposed
cliffs and experience large temporal and spatial variability in water flow throughout
their lifetime. However, it is largely unknown how sea star body shape changes between
wave-exposed and wave-sheltered environments throughout an organism's lifetime.
Wave exposure was measured at sites near Charleston, OR using dissimilar metal
dissolution and intertidal zonation of sessile organisms. At these same sites, I measured
shapes and sizes of Pisaster juveniles and adults and analyzed how morphology
changed as a function of wave exposure.
Average zinc anode mass loss differed significantly between sites during
seasonal trials (p < 0.001 ). Mean upper intertidal zone limits were significantly higher
at the Middle Cove and 01MB Boathouse sites for Ba/anus g/andula (p < 0.01 ), Mytilus
spp. (p < 0.01), Neorlwdomela oregona (p < 0.001), and Sacclwrina sessilis (p < 0.05).
Adult sea star populations the Middle Cove site had longer, narrower arms (p < 0.00 l)
and smaller central discs (p < 0.001) than individuals from the 01MB Boathouse or
Bastendorff Jetty sites for a given weight. Juveniles appeared to exhibit similar
morphological trends to respective adult populations but results were inconclusive. The
lack of a significant relationship between wave exposure and Pisaster morphology is
likely due to errors in measurements of exposure and demonstrates that exposure alone
does not determine body shape.
Beschreibung
52 pages. A thesis presented to the Department of Biology and the Clark Honors College of the University of Oregon in partial fulfillment of the requirements for degree of Bachelor of Science, Spring 2016.
Schlagwörter
Marine biology, Pisaster ochraceus, Wave exposure, Morphology, Zinc dissolution, Intertidal zonation, Aspect ratio